Vehicle control apparatus and vehicle control method

ABSTRACT

A vehicle control apparatus which performs a travel control of a vehicle during a traffic jam, includes a wheel setting unit configured to set at least one wheel to be a brake wheel to be applied with a braking force during the travel control and at least one wheel to be a non-brake wheel not to be applied with the braking force during the travel control, and a control unit configured to perform the travel control of the vehicle based on a rotation amount of the at least one brake wheel and a rotation amount of the at least one non-brake wheel detected by a wheel speed sensor detecting the rotation amount of a wheel of the vehicle.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 14/613,671,filed Feb. 4, 2015 (allowed), which claims priority to JapaneseApplication No. 2014-035715, filed Feb. 26, 2014. The entire disclosuresof the prior applications are considered part of the disclosure of theaccompanying continuation application, and are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a vehicle control apparatus and avehicle control method.

Related Background Art

An automatic parking control apparatus which performs an automaticparking control is known (for example, refer to Japanese UnexaminedPatent Application Publication No. 2008-143337). In the apparatusdisclosed in Japanese Unexamined Patent Application Publication No.2008-143337, the automatic parking control is performed using a detectedvalue of a wheel speed sensor. As the detected value of the wheel speedsensor, a wheel speed pulse is exemplified. In addition, JapaneseUnexamined Patent Application Publication Nos. 2003-534976 and 64-032955are examples of the related art.

SUMMARY OF INVENTION

When a wheel speed pulse is detected, a vehicle speed (wheel speed) iscalculated using a period of a wheel speed pulse, and the calculatedvehicle speed may be used in an automatic parking control of a vehicle.

Incidentally, the period of the wheel speed pulse is long as the vehiclespeed is decreased. Meanwhile, in a state where a wheel is not rotatedand slides on a road surface (a lock state), the wheel speed pulse isnot generated. Accordingly, it may be difficult to determine whether theperiod of the wheel speed pulse is long since the vehicle speed isdecreased or the period of the wheel speed pulse is long since the wheelis locked, as the vehicle speed is decreased. In this way, in theapparatus using the period of the wheel speed pulse, the automaticparking control may not be performed with sufficiently high accuracy.Accordingly, the present invention provides a vehicle control apparatusand a vehicle control method capable of performing an appropriateparking control.

A vehicle control apparatus according to an aspect of the presentinvention is an apparatus that performs a travel control of a vehicleduring a traffic jam. The apparatus includes a wheel setting unit and acontrol unit. The wheel setting unit sets at least one brake wheel whichis a wheel to which a braking force is applied during the parkingcontrol and at least one non-brake wheel which is a wheel to which thebraking force is not applied during the travel control. The control unitperforms the travel control of the vehicle based on a rotation amount ofat least one brake wheel and a rotation amount of at least one non-brakewheel detected by a wheel speed sensor detecting the rotation amount ofa wheel of the vehicle. According to the aspect, it is possible toperform an appropriate travel control.

In the aspect, the control unit may estimate a moving state amount ofthe vehicle based on the rotation amount of at least one non-brakewheel, and may control at least one brake wheel using the moving stateamount of the vehicle. Accordingly, it is possible to perform anappropriate travel control using the moving state amount of the vehicleof improved accuracy.

In the aspect, the moving state amount of the vehicle may be a movementdistance, a speed, an acceleration, or a differential value of theacceleration of the vehicle.

In the aspect, the control unit may determine whether or not the brakewheel is locked based on a difference between the rotation amount of onebrake wheel and the rotation amount of at least one non-brake wheel.According to this configuration, it is possible to accurately determinewhether or not the brake wheel is locked.

In the aspect, when at least one brake wheel is locked, the wheelsetting unit may reset at least one non-brake wheel to the brake wheel.According to this configuration, when the brake wheel is locked, thenon-brake wheel is reset to the brake wheel, and it is possible to applythe braking force to the brake wheel.

In the aspect, when at least one brake wheel is locked, the control unitmay cause a brake actuator to decrease a braking force with respect toone locked brake wheel or a plurality of locked brake wheels, and maycause the brake actuator to apply the braking force to the one resetbrake wheel or the plurality of reset brake wheels. According to thisconfiguration, it is possible to decrease a variation of the brakingforce of the entire vehicle.

In the aspect, the control unit may cause the brake actuator to applythe braking force to the one reset brake wheel or the plurality of resetbrake wheels at a force corresponding to the braking force decreasedwith respect to the one locked brake wheel or the plurality of lockedbrake wheels. According to this configuration, it is possible tocompensate for the decreased braking force by the reset brake wheel.

In the aspect, the wheel setting unit may set at least two non-brakewheels, the control unit may determine whether or not the brake wheel islocked based on the difference between the rotation amount of one brakewheel and the rotation amount of at least one non-brake wheel, and whenthe brake wheel is locked, the wheel setting unit may set at least onenon-brake wheel other than the non-brake wheel, which is used todetermine whether or not the brake wheel is locked, to the brake wheel.According to this configuration, even when the non-brake wheel is resetto the brake wheel and the variation of the braking force in the entirevehicle is decreased, it is possible to accurately understand a movementof the vehicle using the remaining non-brake wheel.

In the aspect, the non-brake wheel may be a wheel to which the brakingforce and a driving force are not applied during the parking control.According to this configuration, it is possible to determine not onlythe locked state of the brake wheel but also a slip state in which thebrake wheel slips.

A vehicle control method according to another aspect of the presentinvention is a method performing a travel control of a vehicle. Themethod includes a set step, a detection step, a determination step, anda control step. In the set step, at least one brake wheel which is awheel to which a braking force is applied during the travel control andat least one non-brake wheel which is a wheel to which the braking forceis not applied during the travel control are set. In the detection step,a rotation amount of at least one brake wheel and a rotation amount ofat least one non-brake wheel are detected using a wheel speed sensor. Inthe determination step, whether or not the brake wheel is locked isdetermined based on the rotation amount of at least one brake wheel andthe rotation amount of at least one non-brake wheel detected in thedetection step. In the control step, a predetermined braking force isapplied to the brake wheel when it is determined that the brake wheel isnot locked in the determination step, and a braking force smaller thanthe predetermined braking force is applied to the brake wheel when it isdetermined that the brake wheel is locked in the determination step.According to the aspect, it is possible to perform an appropriate travelcontrol.

As described above, according to various aspects of the presentinvention, it is possible to appropriately perform a travel control.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a configuration of a vehicle includinga vehicle control apparatus according to an embodiment.

FIG. 2 is a detection result of a wheel speed pulse of a brake wheelwhen a wheel is locked.

FIG. 3 is a detection result of a wheel speed pulse of a non-brake wheelwhen a wheel is locked.

FIG. 4 is a detection result showing integrated values of wheel speedpulses of the brake wheel and the non-brake wheel when the wheel islocked.

FIG. 5 is a flowchart showing an operation of the vehicle controlapparatus shown in FIG. 1.

FIG. 6 is a flowchart showing the operation of the vehicle controlapparatus shown in FIG. 1.

FIG. 7 is a block diagram showing the operation of the vehicle controlapparatus shown in FIG. 1.

FIG. 8 is a graph showing a relationship between an integrated valuedifference and a correction amount of a longitudinal force.

FIG. 9 is a graph showing a relationship between the differential valueof the integrated value difference and the correction amount of thelongitudinal force.

FIG. 10 is a graph showing a relationship between the second orderdifferential value of the integrated value difference and the correctionamount of the longitudinal force.

FIG. 11 is a flowchart showing an operation of a vehicle controlapparatus according to a second embodiment.

FIG. 12 is a schematic diagram illustrating distribution of a brakingforce.

FIG. 13 is a block diagram showing a configuration of a vehicleincluding a vehicle control apparatus according to a third embodiment.

FIG. 14 is a block diagram showing a configuration of a vehicleincluding a vehicle control apparatus according to a fourth embodiment.

FIG. 15 is a detection result of the wheel speed pulse of the brakewheel when the wheel slips.

FIG. 16 is a detection result of the wheel speed pulse of the non-brakewheel when the wheel slips.

FIG. 17 is a result showing the integrated value of the wheel speedpulse of the brake wheel and the non-brake wheel when the wheel slips.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, various embodiments will be described in detail withreference to the drawings. In addition, in the drawings, the samereference numerals are assigned to the same portions or thecorresponding portions.

First Embodiment

A vehicle control apparatus according to the present embodiment is anapparatus that performs a parking control. The parking control indicatesa control for stopping a vehicle at a target parking position. Theparking control includes an automatic parking control which controls thevehicle and automatically stops the vehicle at the parking position, acontrol which performs only assistance of the parking by notification orthe like to a driver, and a control which causes the driver and vehicleequipment to cooperatively operate and assists the parking. Moreover,hereinafter, the case where the vehicle control apparatus performs theautomatic parking control is described as an example. In addition, theparking control includes not only the control until the vehicle isparked at the target parking position but also a control which moves thevehicle to a static steering place or the like required for the parking.

The vehicle control apparatus performs a control which applies a brakingforce to at least a wheel in the parking control. In addition, ifnecessary, the vehicle control apparatus performs a control whichapplies a driving force to the wheel or a control of steering. Moreover,the parking control may be performed on the assumption that the vehicleis travelled at a low speed or the vehicle is stopped. For example, thelow speed may be a speed of 2 km/h or less.

First, an outline of a configuration of a vehicle control apparatus 1will be described. FIG. 1 is a block diagram showing a configuration ofa vehicle 2 including the vehicle control apparatus 1 according to thepresent embodiment. For example, as shown in FIG. 1, the vehicle 2includes a surrounding environment information acquisition device 3, anoperation unit 4, and ECU 5. ECU 5 is a computer of an automobile deviceperforming an electronic control, and is configured to include memorysuch as a processor (Central Processing Unit (CPU)), Read Only Memory(ROM), or Random Access Memory (RAM), an input-output interface, or thelike.

Here, the vehicle 2 is a vehicle including 4 wheels. That is, thevehicle 2 include a FR wheel 6A, a FL wheel 6B, a RR wheel 6C, and a RLwheel 6D. The FR wheel 6A is a right front wheel of the vehicle 2. TheFL wheel 6B is a left front wheel of the vehicle 2. The RR wheel 6C is aright rear wheel of the vehicle 2. The RL wheel 6D is a left rear wheelof the vehicle 2.

In the vehicle 2, a sensor for detecting a rotation amount of each wheelis provided. A wheel speed sensor 7A detects the rotation amount of theFR wheel 6A. A wheel speed sensor 7B detects the rotation amount of theFL wheel 6B. A wheel speed sensor 7C detects the rotation amount of theRR wheel 6C. A wheel speed sensor 7D detects the rotation amount of theRL wheel 6D. The wheel speed sensor 7A outputs a wheel speed pulsesignal in proportion to the rotation amount (the number of revolutionsof an axle per unit time) of the wheel. The number of wheel speed pulsesper rotation of the wheel is set in advance. That is, the number ofwheel speed pulses is correlation with the rotation amount of the wheel.The wheel speed sensor 7A outputs the wheel speed pulse signal to theECU 5. The wheel speed sensors 7B to 7D are configured to be similar tothe wheel speed sensor 7A.

The surrounding environment information acquisition device 3 acquiressurrounding environment information which is surrounding information ofthe vehicle 2. The surrounding environment information is informationincluding position information of the vehicle 2, position information ofan object existing around the vehicle 2, classification information ofthe object, road information in a travelling direction of the vehicle 2,road surface information, white line information, traffic information,or the like. The position information of a parking section line definingthe parking position may be included in the while line information.Moreover, a wall or the like defining the parking section may beincluded in the object existing around the vehicle 2. For example, asthe surrounding environment information acquisition device 3, GlobalPositioning System (GPS) device, a camera, radar, or the like may beused. The GPS is a measurement system using a satellite, and is used foracquiring the position information of the vehicle 2. The surroundingenvironment information acquisition device 3 outputs the surroundingenvironment information to the ECUS.

The operation unit 4 receives an operation of the driver for adjustingthe braking force. For example, the operation unit 4 is a brake pedal.The braking force is a force which is applied to the wheel to deceleratethe vehicle 2 in the longitudinal direction. The operation unit 4outputs the signal according to the operation of the driver to the ECU5.

For example, in addition to the vehicle control apparatus 1, the ECU 5includes a target path calculation unit 8, a target longitudinal forcecalculation unit 9, and a rotation amount acquisition unit 10.

The target path calculation unit 8 calculates a target path of thevehicle 2. The target path is a travelling path until the targetposition. For example, the target position is a target parking positionor an intermediate point set until the target position. For example, thetarget path calculation unit 8 may calculate a path from a currentposition of the vehicle 2 to the parking position based on theinformation output by the surrounding environment informationacquisition device 3. In addition, when a navigation system is mountedon the vehicle 2, or when the vehicle 2 is configured to communicationwith the navigation system, the target path calculation unit 8 mayacquire the target path of the vehicle 2 from the navigation system. Thetarget path calculation unit 8 outputs the target path to the targetlongitudinal force calculation unit 9.

The rotation amount acquisition unit 10 is connected to the wheel speedsensors 7A to 7D, and acquires the rotation amount of each of the FRwheel 6A, the FL wheel 6B, the RR wheel 6C, and the RL wheel 6D. Therotation amount acquisition unit 10 may store the wheel speed pulsesignals obtained from the wheel speed sensors 7A to 7D in time series.The rotation amount acquisition unit 10 outputs the wheel speed pulsesignals to the target longitudinal force calculation unit 9 and thevehicle control apparatus 1.

The target longitudinal force calculation unit 9 calculates a targetlongitudinal force of the vehicle 2. The target longitudinal force isthe longitudinal force which is the target of the vehicle 2. Thelongitudinal force is the force in the longitudinal direction which isapplied to the wheels of the vehicle 2 to accelerate and decelerate thevehicle 2 in the longitudinal direction.

For example, the target longitudinal force calculation unit 9 calculatesthe target longitudinal force of the vehicle 2 using the surroundingenvironment information. For example, the target longitudinal forcecalculation unit 9 calculates the target longitudinal force of thevehicle 2 based on the position information of the vehicle 2, and theposition information of the parking section line defining the parkingposition. Alternatively, for example, the target longitudinal forcecalculation unit 9 may calculate the target longitudinal force when thevehicle 2 travels on the target path for each travelling position basedon the target path of the vehicle 2 output by the target pathcalculation unit 8. Alternatively, for example, the target longitudinalforce calculation unit 9 may calculate the target longitudinal forcewhen the vehicle 2 travels on the target path for each travellingposition based on the target path of the vehicle 2 output by the targetpath calculation unit 8 or the rotation amount of each wheel acquired bythe rotation amount acquisition unit 10. Alternatively, for example, thetarget longitudinal force calculation unit 9 may calculate the targetlongitudinal force based on the signal according to the operation of thedriver output by the operation unit 4. For example, the targetlongitudinal force calculation unit 9 may calculate the targetlongitudinal force based the signal according to the operation of thebrake pedal of the driver. Moreover, for example, the targetlongitudinal force calculation unit 9 may calculate the targetlongitudinal force based the signal according to the operation of anaccelerator pedal of the driver. The target longitudinal forcecalculation unit 9 outputs the target longitudinal force to the vehiclecontrol apparatus 1.

The vehicle control apparatus 1 is an apparatus which assists theparking of the vehicle 2. For example, the vehicle control apparatus 1applies the driving force and the braking force to the wheels to parkthe vehicle at a target parking position based on the target path andthe target longitudinal force. For example, the vehicle controlapparatus 1 includes a wheel setting unit 11 and a control unit 12. Forexample, the control unit 12 includes a braking force applying unit 13and a lock determination unit 14.

The wheel setting unit 11 sets at least one brake wheel which is a wheelto which the braking force is applied during the parking control and atleast one non-brake wheel which is a wheel to which the braking force isnot applied during the parking control from the wheels included in thevehicle 2. For example, the wheel setting unit 11 may set the brakewheel and the non-brake wheel based on the instruction information ofthe driver or the like, and may set the brake wheel and the non-brakewheel based on the surrounding environment information or results of thecontrol in the vehicle 2. Here, “during the parking control” means themiddle of the control assisting a process until the vehicle 2 is parkedto the target parking position. For example, the assist control includesan automatic drive control, a notification control, or a cooperativecontrol with the driver. During the parking control, the vehicle 2 istravelled at a low speed (for example, 2 km/h or less).

The brake wheel is the wheel to which the braking force is applied by abrake actuator (not shown) during the parking control. That is, thebrake wheel is the wheel which becomes an object to which the brakingforce is applied during the parking control. The braking force isapplied by a brake mechanism (not shown) described below and the brakingforce applying unit 13 described below. On the other hand, the non-brakewheel is the wheel to which the braking force is not applied during theparking control regardless of whether or not the wheel is the object tobe braked by the brake mechanism such as the brake actuator. That is,the non-brake wheel is the wheel to which the braking force is notapplied by the brake mechanism (not shown) described below and thebraking force applying unit 13 described below during the parkingcontrol. Moreover, the non-braking wheel may be the wheel to which thebraking force and the driving force are not applied during the parkingcontrol.

For example, the wheel setting unit 11 controls a hydraulic circuit orthe like included in the vehicle 2 and sets the non-brake wheel and thebrake wheel. Alternatively, the wheel setting unit 11 selects thenon-brake wheel and the brake wheel from the plurality of wheels,outputs only the selected results to the braking force applying unit 13described below, and thus, may cause the braking force applying unit 13to distinguish and control the brake wheel and the non-brake wheel.Alternatively, the wheel setting unit 11 may reset the non-brake wheelto the brake wheel based on the results output by the lock determinationunit 14 described below. The wheel setting unit 11 may set the non-brakewheel and the brake wheel during the parking control, and may set thenon-brake wheel and the brake wheel at an appropriate timing before theparking control. The wheel setting unit 11 outputs the settinginformation indicating the non-brake and the brake wheel to the brakingforce applying unit 13.

For example, the braking force applying unit 13 calculates the brakingforce applied to the wheel during the parking control. The braking forceapplying unit 13 may calculate the braking force applied to the wheelbased on the target longitudinal force output by the target longitudinalforce calculation unit 9. Moreover, the braking force applying unit 13controls the brake actuator or the like based on the setting informationoutput by the wheel setting unit 11, and may apply the braking force toonly the brake wheel. For example, the RR wheel 6C and the RL wheel 6Dare set to the brake wheels, and the FR wheel 6A and the FL wheel 6B areset to the non-brake wheel by the wheel setting unit 11. In this case,the braking force applying unit 13 applies the braking force to the RRwheel 6C and the RL wheel 6D and does not apply the braking force to theFR wheel 6A and the FL wheel 6B during the parking control.

In addition, the braking force applying unit 13 may change the brakingforce with respect to the brake wheel based on the results output by thelock determination unit 14. The lock determination unit 14 determineswhether or not the brake wheel is locked based on the rotation amountsof the brake wheel and the non-brake wheel acquired by the rotationamount acquisition unit 10. The lock state indicates a state where thewheels are not rotated on a road surface and slide on the road surface.For example, the lock state is easily generated when a frictioncoefficient of the road surface is small.

FIG. 2 is a graph showing a detection result of a wheel speed pulse ofthe brake wheel when the wheel is locked, in time series. The verticalaxis indicates a wheel speed pulse value, and the horizontal axisindicates a time. FIG. 3 is a graph showing a detection result of awheel speed pulse of the non-brake wheel when the wheel is locked, intime series. The vertical axis indicates a wheel speed pulse value, andthe horizontal axis indicates a time. FIG. 4 is a graph showing anintegrated value of the wheel speed pulse of the brake wheel and anintegrated value of the wheel speed pulse of the non-brake wheel, intime series. The integrated value of the wheel speed pulse means anintegrated value of pulse signals. The vertical axis indicates theintegrated value of the wheel speed pulse, and the horizontal axisindicates a time. FIGS. 2 to 4 correspond to one another by the sametime axes.

As shown in FIG. 2, when the brake wheel is locked from a time ti, thewheel is not rotated, and thus, the wheel speed pulse is not detected.On the other hand, as shown in FIG. 3, the non-brake wheel is correctlyrotated according to the movement of the vehicle 2 even after the timeti, and thus, the wheel speed pulse is detected. The lock determinationunit 14 determines whether or not the brake wheel is locked based on adifference between the wheel speed pulse of the brake wheel and thewheel speed pulse of the non-brake wheel. Specifically, as shown in FIG.4, the lock determination unit 14 may determine whether or not the brakewheel is locked based on a difference d between the integrated value ofthe wheel speed pulse of the brake wheel and the integrated value of thewheel speed pulse of the non-brake wheel. The lock determination unit 14outputs the determination result to the braking force applying unit 13.In a case of the determination result in which the brake wheel islocked, the braking force applying unit 13 decreases the braking forcewith respect to the brake wheel, and may perform a control whichreleases the lock state of the brake wheel. Alternatively, the lockdetermination unit 14 calculates the correction amount of the brakingforce required for the control which releases the lock state, and mayoutput the calculation value to the braking force applying unit 13. Thebraking force applying unit 13 may correct the braking force based onthe correction amount.

In this way, the control unit 12 controls at least one brake wheel basedon the rotation amount of at least one brake wheel and the rotationamount of at least one non-brake wheel. Moreover, the control unit 12estimates the vehicle speed of the vehicle 2 from the rotation amount ofat least one non-brake wheel, and may perform the parking assistanceusing the estimated vehicle speed.

Next, an operation of the vehicle control apparatus 1 will be described.FIG. 5 is a flowchart showing the operation of the vehicle controlapparatus 1. For example, the flowchart shown in FIG. 5 starts at atiming when the signal of the parking assistance starting, in which thevehicle 2 is parked at the target parking position, is input to thevehicle control apparatus 1, and the flowchart is repeatedly performedat a predetermined interval. Moreover, a procedure shown in FIG. 5becomes a vehicle control method of the vehicle 2.

As shown in FIG. 5, initially, wheel setting processing is performed(S10: set step). In the processing of S10, the wheel setting unit 11sets the brake wheel and the non-brake wheel. For example, the wheelsetting unit 11 sets the RR wheel 6C and the RL wheel 6D to the brakewheels, and sets the FR wheel 6A and the FL wheel 6B to the non-brakewheels. When the processing of S10 ends, the step is transferred toenvironment information acquisition processing (S12).

In the processing of S12, for example, as the surrounding environmentinformation, the surrounding environment information acquisition device3 acquires the position information of the parking section line, a walldefining the parking section, or the like required for the parkingassistance. When the processing of S12 ends, the step is transferred totarget movement path calculation processing (S14).

In the processing of the S14, the target path calculation unit 8calculates the target path until the target parking position of thevehicle 2 based on the surrounding environment information acquired bythe processing of S12. When the processing of S14 ends, the step istransferred to rotation amount acquisition processing (S16: detectionstep).

In the processing of S16, for example, the rotation amount acquisitionunit 10 acquires the rotation amounts of the RR wheel 6C and the RLwheel 6D which are the brake wheels and the rotation amounts of the FRwheels 6A and the FL wheels 6B which are the non-brake wheels, and therotation amounts are detected by the wheel speed sensors 7A to 7D.Moreover, the rotation amount acquisition unit 10 may acquire therotation amount of only one non-brake wheel selected from the pluralityof non-brake wheels. That is, the rotation amount acquisition unit 10may acquire the rotation amount of any one of the FR wheel 6A and the FLwheel 6B. When the processing of Step 16 ends, the step is transferredto target longitudinal force calculation processing (S18).

In the processing of S18, the target longitudinal force calculation unit9 calculates the target longitudinal force of the vehicle based on thetarget movement path obtained by the processing of S14 and the rotationamount obtained by the processing of S16. When the processing of S18ends, the step is transferred to input determination processing of thecorrection amount (S20).

In the processing of S20, the braking force applying unit 13 determineswhether or not the correction amount is input to the braking forcedetermined from the target longitudinal force calculated in theprocessing of S20. The calculation processing of the correction amountwill be described below. In the processing of S20, when the correctionamount is not input, the step is transferred to braking force controlprocessing which is not accompanied by the correction of the brakingforce (S22: control step).

In the processing of S22, the braking force applying unit 13 operatesthe brake actuator or the like with respect to the RR wheel 6C and theRL wheel 6D which are the brake wheels, and applies the braking force tothe wheels. For example, the braking force applying unit 13 generatesthe braking force during the parking control, and stops the vehicle 2.In addition, the control unit 12 estimates the moving state amount ofthe vehicle 2 using any one of the FR wheel 6A and the FL wheel 6B whichare the non-brake wheels, and may control the RR wheel 6C and the RLwheel 6D which are the brake wheels using the moving state amount. Themoving state amount of the vehicle 2 is the movement distance, thespeed, the acceleration, and the differential value of the accelerationof the vehicle 2. When the processing of S22 ends, the controlprocessing shown in FIG. 5 ends.

On the other hand, in the processing of S20, when the correction amountis input, the step is transferred to the braking force controlprocessing which is accompanied by the correction of the braking force(S24: control step). In the processing of the S24, the braking forceapplying unit 13 corrects the braking force to be smaller than apredetermined braking force before the correction using the correctionamount, and operates the brake actuator or the like with respect to theRR wheel 6C and the RL wheel 6D which are the brake wheels and appliesthe corrected braking force to the wheels. For example, the brakingforce applying unit 13 generates the braking force during the parkingcontrol, and stops the vehicle 2. In addition, the control unit 12estimates the vehicle speed using any one of the FR wheel 6A and the FLwheel 6B which are the non-brake wheels, and may control the RR wheel 6Cand the RL wheel 6D which are the braking wheels using the vehiclespeed. When the processing of S24 ends, the control processing shown inFIG. 5 ends.

As above, the control processing shown in FIG. 5 ends. As shown in FIG.5, the braking force is applied to only the brake wheel by the brakingforce applying unit 13 during the parking control. Moreover, the vehiclespeed is estimated based on the detection result of the non-brake wheelduring the parking control by the control unit 12, and the vehicle speedis used for the parking assistance. Accordingly, it is possible toperform appropriate braking using a correct vehicle speed.

Next, the determination processing of the lock state and the calculationprocessing of the correction amount of the braking force will bedescribed in detail. FIG. 6 is a flowchart illustrating an operation ofthe lock determination unit 14. For example, the flowchart shown in FIG.6 starts at the timing when the signal of the parking assistancestarting is input to the vehicle control apparatus 1, and the flowchartis repeatedly performed at a predetermined interval. Moreover, aprocedure shown in FIG. 6 becomes a vehicle control method of thevehicle 2.

As shown in FIG. 6, initially, wheel setting processing is performed(S30). The processing of S30 is similar to the processing of S10. Forexample, the wheel setting unit 11 sets the RR wheel 6C and the RL wheel6D to the brake wheels, and sets the FR wheel 6A and the FL wheel 6B tothe non-brake wheels. When the processing of S10 is performed, theprocessing of S30 may be omitted. When the processing of S30 ends, thestep is transferred to rotation amount acquisition processing (S32).

In the processing of S32, the rotation amount acquisition unit 10acquires the rotation amounts of the RR wheel 6C and the RL wheel 6Dwhich are the brake wheels and the rotation amounts of the FR wheel 6Aand the FL wheel 6B which are the non-brake wheels. The processing ofS32 is similar to the processing of S16. Accordingly, when theprocessing of S16 is performed, the processing of S32 may be omitted.When the processing of S32 ends, the step is transferred to theprocessing in which whether or not the wheel is locked is determined(S34: determination step).

In the processing of S34, the lock determination unit 14 compares thewheel speed pulse of the non-brake wheel and the wheel speed pulse ofthe brake wheel for each brake wheel, and determines whether or not thebrake wheel is locked. Hereinafter, initially, the determinationprocessing with respect to the RR wheel 6C will be described.

FIG. 7 is a block diagram showing details of the determinationprocessing and the details of the calculation processing of the brakingforce correction amount. As shown in FIG. 7, initially, the lockdetermination unit 14 calculates the integrated value of the wheel speedpulse of the brake wheel which is the object to be processed. That is,the lock determination unit 14 calculates the integrated value of thewheel speed pulse of the RR wheel 6C. Next, the lock determination unit14 calculates the integrated value of the wheel speed pulse of thenon-brake wheel. When the plurality of non-brake wheels exist, the lockdetermination unit 14 calculates the wheel speed pulse of at least onenon-brake wheel. When the wheel speed pulses of the plurality ofnon-brake wheels are used, the lock determination unit 14 averages theintegrated values of the wheel speed pulses of the non-brake wheels, andcalculates an average integrated value of the wheel speed pulses of thenon-brake wheels. For example, the lock determination unit 14 calculatesthe integrated value of the wheel speed pulse of the FR wheel 6A and theintegrated value of the wheel speed pulse of the FL wheel 6B, andcalculates the average integrated value (average processing 220).

Next, the lock determination unit 14 calculates the difference betweenthe integrated value (or the average integrated value) of the non-brakewheels and the integrated value of the brake wheels. Moreover, the lockdetermination unit 14 may calculate a differential value of theintegrated value differences (differential processing 221). In addition,the lock determination unit 14 may calculate a second order differentialvalue of the differences of the integrated values (differentialprocessing 222). The lock determination unit 14 determines the lockstate of the RR wheel 6C which is the brake wheel using at least one ofthe integrated value differences, the differential value of theintegrated value differences, and the second order differential value ofthe integrated value differences. Here, when the integrated valuedifference is defined as A, the difference value of the integrated valuedifferences is defined as B, and the second order differential value ofthe integrated value difference is defined as C, and if threshold valuesfor determining the lock states are defined as K1, K2, and K3,respectively, for example, whether or not it is a lock state isdetermined by using the following Expressions (lock determinationprocessing 223).

Integrated Value Difference A>First Threshold Value K1   (1)

Differential Value B of Integrated Value Difference>Second ThresholdValue K2   (2)

Second Order Differential Value C of Integrated Value Difference>ThirdThreshold Value K3   (3)

In the above, the first threshold value K1, the second threshold valueK2, and the third threshold value K3 are threshold values fordetermining the lock states, and for example, are predetermined valuesdetermined in advance by an actual measurement value. When any one ofExpressions (1) to (3) is satisfied, the lock determination unit 14 maydetermine that the RR wheel 6C which is the brake wheel is locked.Alternatively, Expression in which two or more inequalities selectedfrom the three inequalities are combined by an AND condition or an ORcondition is prepared, and when Expression is satisfied, the lockdetermination unit 14 may determine that the RR wheel 6C which is thebrake wheel is locked. The lock determination unit 14 performs similarprocessing with respect to all brake wheels set in the vehicle 2.

Returning to the processing of S34 of FIG. 6, when the lockdetermination unit 14 determines that the lock state is not generated,the control processing shown in FIG. 6 ends. On the other hand, when thelock determination unit 14 determines that the lock state is generated,the step is transferred to braking force correction amount calculationprocessing (S36).

In the processing of S36, the lock determination unit 14 calculates thecorrection amount which decreases the braking force and can release thelock state of the brake wheel. As shown in FIG. 7, the lockdetermination unit 14 calculates the correction amount of the RR wheelwhich is the brake wheel using at least one of the integrated valuedifferences, the differential value of the integrated value differences,and the second order differential value of the integrated valuedifferences (braking force correction amount calculation processing224).

For example, the lock determination unit calculates the correctionamount of the braking force using a graph shown in FIG. 8. FIG. 8 is thegraph showing the relationship between the integrated value differenceand the longitudinal force correction amount. The horizontal axisindicates an input value (integrated value difference), and the verticalaxis indicates the longitudinal force correction amount. FIG. 9 is agraph showing a relationship between the difference value of theintegrated value differences and the longitudinal force correctionamount. The horizontal value indicates an input value (the differencevalue of the integrated value differences), and the vertical axisindicates the longitudinal force correction amount. FIG. 10 is a graphshowing a relationship between the second order differential value ofthe integrated value differences and the longitudinal force correctionamount. The horizontal axis indicates an input value (the second orderdifferential value of the integrated value differences), and thevertical axis indicates the longitudinal force correction amount.

As shown in FIG. 8, when the integrated value difference is a positivevalue d1, the longitudinal force correction amount becomes a positivevalue F1. When the integrated value difference is the positive value d1,since the brake wheel is locked, it is necessary to add a positive valuewith respect to the braking force having a negative value and decreasean absolute value of the braking force. Accordingly, the lockdetermination unit 14 adds the positive value F1 in the front directionof the vehicle to the braking force (negative value) before thecorrection. Therefore, the corrected braking force is decreased, andthus, it is possible to release the lock state.

In addition, as shown in FIG. 9, when the differential value of theintegrated value difference is a positive value d2, the longitudinalforce correction amount becomes a positive value F2. When thedifferential value of the integrated value differences is the positivevalue d2, since the integrated value difference is gradually increased,it is highly likely that the brake wheel is locked. Accordingly, it isnecessary to add a positive value with respect to the braking forcehaving a negative value and decrease the absolute value of the brakingforce. Therefore, the lock determination unit 14 adds the positive valueF2 in the front direction of the vehicle to the braking force (negativevalue) before the correction. Accordingly, the corrected braking forceis decreased, and thus, it is possible to release the lock state.

Moreover, as shown in FIG. 10, when the second order difference value ofthe integrated value differences is a positive value d3, thelongitudinal force correction amount becomes a positive value F3. Whenthe second order difference value of the integrated value differences isthe positive value d3, since the integrated value difference is abruptlychanged, it is high likely that the brake wheel is locked. Accordingly,it is considered to add a positive value with respect to the brakingforce having a negative value and decrease the absolute value of thebraking force. Therefore, the lock determination unit 14 adds thepositive value F3 in the front direction of the vehicle to the brakingforce (negative value) before the correction. Accordingly, the correctedbraking force is decreased, and thus, it is possible to release the lockstate.

By adopting any one or the combination of maps shown in FIGS. 8 to 10,it is possible to correct the finally applied braking force to bedecreased. In addition, the lock determination unit 14 is not limited tothe case where the correction amount is calculated using a graph or amap. For example, a gain value is changed with at least one of theintegrated value differences, the difference value of the integratedvalue differences, and the second order difference value of theintegrated value differences as a parameter, and the correction amountof the braking force may be calculated.

When the processing of S36 of FIG. 6 ends, the step is transferred tocorrection amount output processing (S38). In the processing of S38, thelock determination unit 14 outputs the correction amount calculated bythe processing of S36 to the braking force applying unit 13. When theprocessing of S38 ends, the control processing shown in FIG. 6 ends.

By performing the control processing shown in FIG. 6, the lock state ofthe brake wheel is determined using the difference between theintegrated value of the wheel speed pulse of the non-brake wheel and theintegrated value of the wheel speed pulse of the brake wheel.

As described above, in the vehicle control apparatus 1 according to thefirst embodiment, at least one brake wheel and at least one non-brakewheel are set by the wheel setting unit 11. Even when the brake wheel islocked, the non-brake wheel is rotated according to the movement of thevehicle. Accordingly, it is possible to perform appropriate parkingassistance even during the parking control of a relatively low speed byusing the rotation amount of at least one non-brake wheel.

In addition, in the vehicle control apparatus 1 according to the firstembodiment, the control unit 12 estimates the vehicle speed based on therotation amount of at least one non-brake wheel, and may control atleast one brake wheel using the vehicle speed. Compared to the brakewheel, the non-brake wheel is correctly rotated according to themovement of the vehicle. Accordingly, it is possible to estimate anaccurate vehicle speed using the rotation amount of the non-brake wheel.Therefore, it is possible to perform an appropriate brake using theaccurate vehicle speed. Moreover, it is possible to appropriatelyoperate a release system of the lock state such as Anti-lock BrakingSystem (ABS) using the accurate vehicle speed.

Moreover, in the vehicle control apparatus 1 according to the firstembodiment, the control unit 12 determines whether or not the brakewheel is locked based on the difference between the rotation amount ofone brake wheel and the rotation amount of at least one non-brake wheel,and may control the brake wheel based on the determination result. Sincethe non-brake wheel which is more accurately rotated than the brakewheel according to the movement of the vehicle 2 is the reference, it ispossible to accurately determine whether or not the brake wheel islocked.

Second Embodiment

A vehicle control apparatus according to a second embodiment isconfigured to be approximately similar to the vehicle control apparatus1 according to the first embodiment, and is different from the firstembodiment in that the non-brake wheel is reset to the brake wheelduring the parking control, and the braking force is applied to thereset brake wheel. Hereinafter, in consideration of easy understandingof descriptions, differences between the vehicle control deviceaccording to the second embodiment and the vehicle control device 1according to the first embodiment are mainly described, and overlappingdescriptions are omitted.

The configuration of the vehicle control apparatus according to thepresent embodiment is approximately similar to the configurationaccording to the first embodiment, and is different in that thenon-brake wheel is reset to the brake wheel by the wheel setting unit 11during the parking control and the braking force applying unit 13controls the braking force of the entire vehicle including the resetbrake wheel, and other configurations are the same as each other.

The operation of the vehicle control apparatus according to the presentembodiment is similar to that of the vehicle control apparatus 1according to the first embodiment shown in FIGS. 5 and 6. Accordingly,only processing of a wheel set change will be described in detail. FIG.11 is a flowchart of the operation of the vehicle control apparatus 1according to the present embodiment. The flowchart shown in FIG. 11 isapproximately similar to the flowchart shown in FIG. 6, and only thewheel set change processing is different.

As shown in FIG. 11, initially, wheel setting processing is performed(S40). The processing of S40 is similar to the processing of S30. Forexample, the wheel setting unit 11 sets the RR wheel 6C and the RL wheel6D to the brake wheels, and sets the FR wheel 6A and the FL wheel 6B tothe non-brake wheels. When the processing of S10 and S30 is performed,the processing of S40 may be omitted. When the processing of S40 ends,the step is transferred to rotation amount acquisition processing (S42).

In the processing of S42, the rotation amount acquisition unit 10acquires the rotation amounts of the RR wheel 6C and the RL wheel 6Dwhich are the brake wheels and the rotation amounts of the FR wheel 6Aand the FL wheel 6B which are the non-brake wheels. The processing ofS42 is similar to the processing of S32. Accordingly, when theprocessing of S32 is performed, the processing of S42 may be omitted.When the processing of S42 ends, the step is transferred to theprocessing in which whether or not the wheel is locked is determined(S44).

In the processing of S44, the lock determination unit 14 compares thewheel speed pulse of the non-brake wheel and the wheel speed pulse ofthe brake wheel for each brake wheel, and determines whether or not thebrake wheel is locked. The processing of S44 is similar to theprocessing of S34. When the lock determination unit 14 determines thatthe lock state is not generated, the control processing shown in FIG. 11ends. On the other hand, when the lock determination unit 14 determinesthat the lock state is generated, the step is transferred to brakingforce correction amount calculation processing (S46).

In the processing of S46, the lock determination unit 14 calculates thecorrection amount which decreases the braking force and can release thelock state of the brake wheel. The processing of S46 is similar to theprocessing of S36. When the processing of S46 ends, the step istransferred to output processing (S48).

In the processing of S48, the lock determination unit 14 outputs thecorrection amount calculated by the processing of S46 to the brakingforce applying unit 13. When the processing of S48 ends, the step istransferred to the wheel set change processing (S50).

In the processing of S50, the wheel setting unit 11 resets the non-brakewheel to the brake wheel. For example, the wheel setting unit 11 resetsthe FR wheel 6A and the FL wheel 6B which are the non-brake wheels tothe brake wheels. Here, the reset wheels may be all non-brake wheels, ormay be a portion of all non-brake wheels. That is, the wheel settingunit 11 may reset only the FR wheel 6A to the brake wheel, and may resetonly the FL wheel 6B to the brake wheel. When the processing of S50ends, the control processing shown in FIG. 11 ends.

By performing the control processing shown in FIG. 11, when at least onebrake wheel is locked, at least one non-brake wheel is reset to thebrake wheel by the wheel setting unit 11. Accordingly, it is possible tonewly apply the braking force to the reset brake wheel. Therefore, evenwhen the brake wheel is locked, it is possible to appropriately performthe parking control using the reset brake wheel.

The control of the braking force of the braking force applying unit 13before and after the resetting is performed will be described. FIG. 12is a graph showing how the braking force of the entire vehicle ischanged before and after the lock is generated. The horizontal axisindicates a time, and the vertical axis indicates the braking force ofthe entire vehicle. Here, before a time t2, the RR wheel 6C and the RLwheel 6D are set to the brake wheels, and the FR wheel 6A and the FLwheel 6B are set to the non-brake wheels. Moreover, at the time t2, theRR wheel 6C and the RL wheel 6D are locked, and only the FR wheel 6A isreset to the brake wheel. The braking force applying unit 13 distributesthe braking forces of the entire vehicle to the brake wheels, andcontrols each brake wheel by a distributed braking force. When thebraking force of the entire vehicle before the lock is generated isdefined as F4, the braking force applying unit 13 distributes thebraking force F4 to the RR wheel 6C and the RL wheel 6D, and controlsthe RR wheel 6C and the RL wheel 6D by the distributed braking force.

Here, when the RR wheel 6C and the RL wheel 6D are locked, the brakingforce applying unit 13 decreases the braking force with respect to theRR wheel 6C and the RL wheel 6D to release the lock state. However, inthis case, the braking force of the entire vehicle is likely to besmaller than the initial braking force F4. When the braking force of theentire vehicle is smaller than the initial braking force F4, there is aconcern that variation in accelerations accompanied by the change of thebraking force may be increased. Accordingly, the braking force applyingunit 13 applies the brake wheel to the reset FR wheel 6A. According tothis configuration, even when the braking force is decreased to releasethe lock state of the brake wheel, it is possible to decrease thevariation in the braking forces of the entire vehicle. The braking forceapplying unit 13 may distribute the braking force to the reset brakewheel so that the braking force of the entire vehicle is not changedbefore and after the lock state. That is, the braking force applyingunit 13 may apply the braking force to the one reset or plurality ofreset brake wheels corresponding to the braking force decreasing withrespect to the locked brake wheel. For example, when the braking forceF4 is the same as an addition value between a braking force F40 and abraking force F41, the braking force F40 is applied to the RR wheel 6Cand the RL wheel 6D, and the braking force F41 is applied to the FRwheel 6A by the braking force applying unit 13. According to thisconfiguration, even when the braking force is decreased to release thelock state of the brake wheel, the reset brake wheel can compensate forthe decreased braking force. Accordingly, it is possible to prevent thebraking force of the entire vehicle from being changed.

Moreover, as described above, when only one of two non-brake wheels ischanged to the brake wheel, after the resetting is performed, onenon-brake wheel exists. In this way, regardless of the processing of theresetting, by securing at least one non-brake wheel, even when thenon-brake wheel is reset to the brake wheel and the variation in thebraking force of the entire vehicle is prevented, it is possible toaccurately understand the movement of the vehicle using the remainingnon-brake wheel. Accordingly, it is possible to prevent the brakingforce of the entire vehicle from being changed and to accuratelydetermine whether or not the brake wheel is locked.

Third Embodiment

A vehicle control apparatus 1A according to a third embodiment isconfigured to be approximately similar to the vehicle control apparatus1 according to the first embodiment, and is different from the firstembodiment in that a lock determination unit 14A is operated usinginformation acquired by a steering sensor. Hereinafter, in considerationof easy understanding of descriptions, differences between the vehiclecontrol device according to the third embodiment and the vehicle controldevice 1 according to the first embodiment are mainly described, andoverlapping descriptions are omitted.

The configuration of the vehicle control apparatus 1A according to thepresent embodiment is approximately similar to the configurationaccording to the first embodiment, and the function of the lockdetermination unit 14A is different from each other.

As shown in FIG. 13, the vehicle 2 includes a steering sensor 15. Thesteering sensor 15 is a sensor which detects a steering angle of ahandle. The steering sensor 15 outputs the steering angle to the lockdetermination unit 14.

A basic operation of the lock determination unit 14A is the same as theoperation of the lock determination unit 14. The lock determination unit14A determines whether or not the brake wheel is locked considering thesteering angle. For example, when the vehicle 2 travels on a curvedroad, even though the lock state is not generated, the rotation amountin the inner wheel of the curve and the rotation amount in the outerwheel of the curve may be different from each other. Accordingly, forexample, when the steering angle is equal to or more than apredetermined value, the lock determination unit 14 performs the lockdetermination in a state of expecting the difference between therotation amounts of the non-brake wheel and the brake wheel generated bythe curve in advance. For example, the lock determination unit 14Asubtracts the difference between the rotation amounts generated by thecurve when the steering angle is equal to or more than a predeterminedvalue from the current difference, and performs the lock determinationusing the subtracted value.

In addition, the lock determination unit 14A may change the thresholdvalue used for the lock determination considering the steering angle.For example, the lock determination unit 14A may set the first thresholdvalue K1, the second threshold value K2, and the third threshold valueK3 greatly as the steering angle is increased. In addition, the lockdetermination unit 14A may change the correction amount of the brakingforce according to the steering angle. For example, the lockdetermination unit 14A may change the correction amount according to thesteering angle referring to the detected value of the steering sensor15, correction maps which are associated with the steering angle andshown in FIGS. 8 to 10, and the correction map according to the steeringangle. Other configurations of the vehicle control apparatus 1A are thesame as those of the vehicle control apparatus 1.

As described above, according to the vehicle control apparatus 1A of thethird embodiment, since the determination of the rotation amount of eachwheel can be changed according to the steering, it is possible toimprove accuracy of the lock determination. In addition, when the brakewheel is locked, it is possible to reset at least one non-brake wheelother than the non-brake wheel, which is used to determine whether ornot the brake wheel is locked, to the brake wheel. Accordingly, it ispossible to realize accuracy improvement of the vehicle speed whiledetermining the lock state.

As described above, the embodiments are described. However, the presentinvention is not limited to the embodiments. For example, as describedbelow, the present invention may be used in a vehicle travel control.

A vehicle control apparatus 1B performing the vehicle travel control isconfigured to be approximately similar to the vehicle control apparatus1A according to the third embodiment, and is different from the vehiclecontrol apparatus 1A according to the third embodiment in that not onlythe lock determination but also slip determination are performed, notonly the braking force but also the driving force are applied to thewheel, and not only the parking control but also the vehicle travelcontrol are performed. Hereinafter, in consideration of easyunderstanding of descriptions, differences between the vehicle controldevice 1B and the vehicle control device 1 A according to the thirdembodiment are mainly described, and overlapping descriptions areomitted.

The configuration of the vehicle control apparatus 1B performing thevehicle travel control is approximately similar to the configurationaccording to the third embodiment, and is different in that the vehiclecontrol apparatus 1B includes a lock and slip determination unit 14B anda braking force and driving force applying unit 16B. In addition, thevehicle control apparatus 1B is an apparatus which assists the travelaccompanied by the brake, and for example, relates to the travel controlduring a traffic jam when convoy travelling assistance is performed,more specifically, when the vehicle becomes less than or equal to apredetermined speed (for example, 2 km/h or less in a low speed region)and stops. The travel control includes an automatic travel control whichautomatically controls and travels the vehicle, a control which performsonly the assistance of the travel by the notification or the like to thedriver, or a control which causes the driver and vehicle equipment tocooperatively operate and perform the travel assistance.

As shown in FIG. 14, the vehicle control apparatus 1B includes a wheelsetting unit 11B, a lock and slip determination unit 14B, and a brakingforce and driving force applying unit 16B.

Similar to the first embodiment, the wheel setting unit 11B sets thebrake wheel and the non-brake wheel. Here, the non-brake wheel accordingto the present embodiment is a wheel to which the braking force and thedriving force are not applied during the travel control. The brake wheelaccording to the present embodiment is a wheel to which the brakingforce and the driving force are applied during the travel control.

The lock and slip determination unit 14B performs the lock determinationsimilar to the first embodiment. Moreover, the lock and slipdetermination unit 14B performs the slip determination using the wheelspeed pulses of the non-brake wheel and the brake wheel.

FIG. 15 is a graph showing a detection result of the wheel speed pulseof the brake wheel when the wheel slips, in time series. The verticalaxis indicates the wheel speed pulse value, and the horizontal axisindicates a time. FIG. 16 is a graph showing the detection result of thewheel speed pulse of the non-brake wheel when the wheel slips, in timeseries. The vertical axis indicates the wheel speed pulse value, and thehorizontal axis indicates a time. FIG. 17 is a graph showing theintegrated value of the wheel speed pulse of the brake wheel and theintegrated value of the wheel speed pulse of the non-brake wheel, intime series. The integrated value of the wheel speed pulse means anintegrated value of pulse signals. The vertical axis indicates theintegrated value of the wheel speed pulse, and the horizontal axisindicates a time. FIGS. 15 to 17 correspond to one another by the sametime axes.

As shown in FIG. 15, when the brake wheel slips from a time t3, sincethe wheel slips, many wheel pulses are detected. On the other hand, asshown in FIG. 16, the non-brake wheel is correctly rotated according tothe movement of the vehicle 2 even after the time t3, and the wheelspeed pulse is detected. The lock and slip determination unit 14Bdetermines whether or not the brake wheel slips based on the differencebetween the wheel speed pulse of the brake wheel and the wheel speedpulse of the non-brake wheel. Specifically, as shown in FIG. 17, thelock and slip determination unit 14B may determine whether or not thebrake wheel slips based on the difference d between the integrated valueof the wheel speed pulse of the brake wheel and the integrated value ofthe wheel speed pulse of the non-brake wheel. The lock and slipdetermination unit 14B outputs the determination result to the brakingforce and driving force applying unit 13B. In the case of thedetermination result in which the brake wheel slips, the braking forceand driving force applying unit 13B decreases the driving force withrespect to the brake wheel, and may perform the control which releasesthe slip state of the brake wheel. Alternatively, the lock and slipdetermination unit 14B calculates the correction amount of the drivingforce required for the control to release the slip state, and may outputthe correction amount to the braking force and driving force applyingunit 13B. The braking force and driving force applying unit 13B maycorrect the braking force based on the correction amount.

As above, according to the vehicle control apparatus 1B performing thevehicle travel control, it is possible to determine not only the lockstate of the brake wheel but also the slip state in which the brakewheel slips. In addition, for example, even when the brake control isperformed during a traffic jam in which the speed of the vehicle isrelatively low, it is possible to perform appropriate braking.

Moreover, in the embodiments, the examples in which the number of thewheels of the vehicle 2 is 4 are described. However, the number of thewheels is not limited to 4. For example, in the first embodiment, thethird embodiment, and the fourth embodiment, the number of the wheelsmay be 2 or more. Moreover, in the second embodiment, the number of thewheels may be 3 or more.

The embodiments may be performed to be combined. For example, thecontrol in the second embodiment may be applied to the third embodimentor the vehicle travel control performing the slip determination.

In the embodiments, the examples in which the wheel speed sensors areprovided on all wheels are described. However, the wheel speed sensormay not be provided on the wheel which is not used in the control of theparking assistance or the travel assistance.

In the first embodiment, the wheel setting unit 11 may perform the wheelsetting processing before the control shown in FIG. 5 is performed.Alternatively, for example, the wheel setting unit 11 may perform thewheel setting processing between the processing of S12 and theprocessing of S18. FIGS. 6 and 11 are also similarly applied.

In the first embodiment, the lock determination unit 14 may perform thewheel lock determination processing of S34 of FIG. 6 between S36 andS38. FIG. 11 is also similarly applied.

What is claimed is:
 1. A vehicle control apparatus which performs a travel control of a vehicle during a traffic jam, comprising: a wheel setting unit configured to determine at least one wheel to be a brake wheel to be applied with a braking force or a driving force during the travel control and at least one wheel to be a non-brake wheel not to be applied with the braking force and the driving force during the travel control; and a control unit configured to perform the travel control of the vehicle based on a rotation amount of the at least one brake wheel and a rotation amount of the at least one non-brake wheel, wherein the rotation amount of the at least one brake wheel and the rotation amount of the at least one non-brake wheel are detected by respective wheel speed sensors.
 2. The vehicle control apparatus according to claim 1, wherein the control unit estimates a moving state amount of the vehicle based on the rotation amount of the at least one non-brake wheel, and controls the at least one brake wheel using the moving state amount of the vehicle.
 3. The vehicle control apparatus according to claim 2, wherein the moving state amount of the vehicle is a movement distance, a speed, an acceleration, or a differential value of the acceleration of the vehicle.
 4. The vehicle control apparatus according to claim 1, wherein the control unit decides whether or not the at least one brake wheel becomes locked based on a difference between the rotation amount of the at least one brake wheel and the rotation amount of the at least one non-brake wheel.
 5. The vehicle control apparatus according to claim 2, wherein the control unit decides whether or not the at least one brake wheel becomes locked based on a difference between the rotation amount of the at least one brake wheel and the rotation amount of the at least one non-brake wheel.
 6. The vehicle control apparatus according to claim 3, wherein the control unit decides whether or not the at least one brake wheel becomes locked based on a difference between the rotation amount of the at least one brake wheel and the rotation amount of the at least one non-brake wheel.
 7. The vehicle control apparatus according to claim 1, wherein the control unit decides whether or not the at least one brake wheel becomes slipped based on a difference between the rotation amount of the at least one brake wheel and the rotation amount of the at least one non-brake wheel.
 8. The vehicle control apparatus according to claim 2, wherein the control unit decides whether or not the at least one brake wheel becomes slipped based on a difference between the rotation amount of the at least one brake wheel and the rotation amount of the at least one non-brake wheel.
 9. The vehicle control apparatus according to claim 3, wherein the control unit decides whether or not the at least one brake wheel becomes slipped based on a difference between the rotation amount of the at least one brake wheel and the rotation amount of the at least one non-brake wheel.
 10. The vehicle control apparatus according to claim 7, wherein when the at least one brake wheel becomes slipped, the control unit decreases the driving force with respect to the at least one brake wheel that became slipped.
 11. The vehicle control apparatus according to claim 8, wherein when the at least one brake wheel becomes slipped, the control unit decreases the driving force with respect to the at least one brake wheel that became slipped.
 12. The vehicle control apparatus according to claim 9, wherein when the at least one brake wheel becomes slipped, the control unit decreases the driving force with respect to the at least one brake wheel that became slipped. 